diff --git a/src/editfns.c b/src/editfns.c
index 341e241dfcb..4089edb1074 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -4398,7 +4398,7 @@ styled_format (ptrdiff_t nargs, Lisp_Object *args, bool message)
 	      props = extend_property_ranges (props, len, new_len);
 	      /* If successive arguments have properties, be sure that
 		 the value of `composition' property be the copy.  */
-	      if (1 < i && info[i - 1].end)
+	      if (1 <= i && info[i - 1].end)
 		make_composition_value_copy (props);
 	      add_text_properties_from_list (val, props,
 					     make_fixnum (info[i].start));
diff --git a/test/src/editfns-tests.el b/test/src/editfns-tests.el
index 9bdd5cf5db6..e6f80d0ef48 100644
--- a/test/src/editfns-tests.el
+++ b/test/src/editfns-tests.el
@@ -938,4 +938,13 @@ sufficiently large to avoid truncation."
                        (pos-bol 2) (pos-eol 2))
     (should (equal (buffer-string) "toto\nEmacs forever!\n"))))
 
+(ert-deftest editfns-tests--format-composition-property ()
+  "Check that composition properties are un-identified by `format'."
+  (let* ((s (compose-chars ?a ?b ?c))
+         (str (format "%s%s%s" s s s)))
+    (should-not (eq (get-text-property 0 'composition str)
+                    (get-text-property 3 'composition str)))
+    (should-not (eq (get-text-property 3 'composition str)
+                    (get-text-property 6 'composition str)))))
+
 ;;; editfns-tests.el ends here